Process and apparatus for separating intermixed divided materials



March 6, 1934. PEALE r AL 1,949,729

PROCESS AND APPARATUS FOR SEPARATING INTERMIXED DIVIDED MATERIALS Filed Sept. 25, 1930 3 Sheets-Sheet 1 March 6, 1934. R. PEALE El AL PROCESS AND APPARATUS FOR SEPARATING INTERMIXED DIVIDED MATERIALS 3 Sheets-Sheet 2 Filed Sept. 23, 1930 E our E O O Q March 6, 1934. R PEALE Er AL 1,949,729

PROCESS AND APPARATUS FOR SEPARATING INTERMIXED DIVIDED MATERIALS Filed Sept. 23, 1930 3 Sheets-Sheet 5 Patented Mar. 6, 1934 UNITED STATES PATENT OFFICE PROCESS AND APPARATUS FOR SEPARAT- ING INTERMIXED DIVIDED MATERIALS Application September 23, 1930, Serial No. 483,859

9 Claims.

The invention relates to a novel and useful process and apparatus for separating intermixed, divided materials, varying relatively greatly in size, and in certain of its features, the invention has special adaptation to the purification of unsized coal representing difficult problems of purlfication.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instruinentalities and combinations pointed out in the appended claims.

The invention consists in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a part hereof, illustrate one embodiment of the invention, and together with the description, serve to explain the principles of the invention.

Fig. l is a side elevation of a form of mechanism adapted for use in carrying out the invention;

2 is a detached plan view of the subareal air chamber structure beneath the table;

Fig. 3 is a transverse, vertical section taken through Fig. l, substantially on the line 3-3 of Fig. 1;

Fig. i is a top plan of the table showing a form and arrangement of separating partitions embodying the invention;

Fig. 5 is a diagrammatic plan of a table showing variably spaced separating partitions;

Fig. 6 is a detached detail in elevation of one of the separating partitions shown in Fig. 4;

Fig. '7 is a diagrammatic plan of an air zoned table; and

Fig. 8 is a fragmentary, top plan of a part of the table shown in Fig. 4.

Fig. 9 is a longitudinal section on line 9-9 of Fig. 5.

The invention comprises a novel and highly efiicient separating process of the type wherein lifting and loosening air currents and vibratory motion coact on the intermixed particulate or divided materials to efiect separation thereof. Our process, and the preferred mechanism for practicing it, are especially adapted to emciently sepa rate, usually in a single processing intermixed materials which vary relatively greatly in the size range of the pieces or particles; and also materials or" the kind or condition stated presenting further difficulties in that the specific gravities of the intermixed materials are very close, and especially wherein there is a very high proportion of fines, or the fines are relatively very dirty, or there is substantial disproportion of any size or range of sizes in the mixture. The process is especially applicable to, and finds a wide field of usefulness in, the purification of raw, unsized coals, many of which present great difficulties of the kind indicated. In purifying unsized coal, that is, run-of-mine coal, in which only the very large lumps have been crushed or removed (to avoid damage to the mechanism), the size of the coal varies from fine dust to pieces several inches in dimensions, and the slate, rock, sulphur, and other intermixed impurities, likewise often vary through an equally wide range of sizes. In many such coals the relative specific gravities of the coal and impurities vary relatively little, and the gravitational splitting point between the clean coal and the lightest impurities is very close.

The present invention is directed especially to the eificient purification of such coals presenting diificulties due to unusual relative proportions of the fine and coarse materials, and overcomes these difficulties by control and direction of the fiowage or confluence of certain fio-tant materials in the bed and by control of the location and rate of flowage of selected or predetermined sizes or size ranges in the bed.

The present invention even in purifying such difficult materials as raw coals of the kind described, and possessing the refractory characteristics stated, obviates the great amount of mechanism, time and labor required for preliminary sizing as usually practiced, and the subsequent use of as many separating tables as there are sizes of coal thereby produced; which have generally been regarded as essentially prerequisite to the purification of any raw or impure coal, and likewise avoids the resultant great breakage of the coal.

In our present novel process the raw or impure coal is regulably fed to constitute a continually-advancing bed, which, as it advances over an air-pervious deck, is progressively Stratified and thereby separated and purified, through the action of lifting and loosening and floating air currents and the vibration and inclination of the bed.

In purifying many kinds of coal, and especially where substantially complete purification thereof is rendereddiificult by the presence of a relatively large proportion of fine impurities, our invention provides means for preventing and correcting, as they arise, undesirable conditions in the bed which would militate against efiicient purification. For example, a simultaneous sizing or classification of the flotant strata is one of the most usual conditions concomitant with the purifying or separating process. While the simultaneous sizing action is desirable and often necessary in the treatment of many coals, some of the effects thereof, with some coals, may detract from complete purification by interfering with elimination of the fine impurities.

Briefly described, this simultaneous size classification occurs oftentimes as follows:

In the early stages of the stratification of the bed, in many cases the relatively strong air action tends to roughly grade the materials vertically in the bed according to their sizes and weights. The finest coal particles are floated uppermost while the larger coal lumps tend to occupy lower intermediate strata. The largest and heaviest pieces of rock sink rapidly to the table surface, and are almost immediately impelled out of the bed through the rear refuse boxes, while much of the smaller and very fine impurities are temporarily sustained in the intermediate strata with and above the larger coal pieces.

As the bed travels forwardly, the smaller heavy impurities gradually and progressively settle to the table surface through the air-loosened and fluidized bed. However, in the meantime, the larger coal pieces in the lower strata are impelled more or less transversely and outwardly by frictional contact with the transversely-travelling impurities beneath, and by occasional contacts with the tops of the separating partitions. Con currently the freely fiotant fine coal and the temporarily flotant fine impurities, which are above the separating partitions, move more or less transversely toward the inner and lower side of the deck during their forward progress with the bed. If the air pressure is sufficiently strong, the described actions eventually bring about a transverse size classification of the coal, with the largest coal pieces along the outer side of the bed, the finest coal along the lower and inner side thereof, and a more or less complete intervening size classification, so that the coal stratum discharges over the front spillage edge as a stream which is classified transversely as to size.

The finer impurities also will be affected by the size-classifying action, inasmuch as they also float temporarily with the fine coal both forwardly and toward the lower side of the deck. These fine impure partic es gradually sink toward the surface of the table during their forward travel, but in many cases they will not have settled behind a separating partition until they have worked forwardly and inwardly in the bed for a considerable distance. Consequently, and especially when there is a large proportion of fine inrpurities, a considerable proportion of these fine impurities will not sink behind the separating partitions, and so begin to travel across the deck until they have reached a point along the irner and lower side of the deck and near the front end thereof. In such case, these settled fine, heavy particles must travel diagonally, behind the separating paritions, the full width of the table to the refuse boxes along the upper side edge thereof.

This allocation of the fine heavy particles is not conducive to the best purifying action for several reasons. First, the fine particles naturally resist progression or impulsion along a frictional surface and the farther they must travel to discharge the greater is the danger of remixing. Secondly, as the fine heavy particles travel behind a separating partition and beneath the fiotant stratum, they approach the upper side edge of the deck, which is occupied principally by the larger pieces of coal, having a. large proportion of voids or interstices. Consequently, the air passes upwardly relatively freely and rapidly therethrough, and tends to entrain and lift the fine heavy particles above the separating partitions, thereby remixing the fine impurities with the coarse coal above them.

The present invention provides means for preventing and counteracting the tendency of the bed to undergo marked transverse size classifying in cases where such sizing is undesirable, as explained. Accordingly, means are provided for emporarily arresting the forward flovvage of flotant material, whether pure coal or still intermixed materials, and for effecting travel thereof obliquely forwardly toward the high side of the bed. For this purpose, certain separating partitions, and certain parts thereof transversely of the table, are upwardly extended further into the bed for the purpose of somewhat retarding the forward movement of some of the flotant material and also imparting some transverse movement thereto without its having settled on the deck. These upward extensions t us afiect or infiuence some flotant material and thereby change its path of travel and destination upon the table.

Certain of these corrective devices are applied longitudinally of the table at various loci along or adjacent the side edges thereof. The construction function of these are exemplarily shown in Figs. l and. 6. One group of the devi es operates on the flotant material along the inner or lower side of the bed, and acts mainly to displace fine material toward the median part of the bed.

In accordance with certain features of our invention, and in the present preferred commercial practice thereof, it is carried out with a bed of the materials that in passin over a vibrating deck or table is subjected to lifting, loosening and floating air currents which vary gradually, or by steps, between greatest and least intensity. To effect this varying air current intensity we preferably utilize a zoning or gradation of the air perviosity of the table. For most materials we preferably use the air currents of greatest intensity at the rear of the bed, the intensity decreasing gradually forwardly.

Further, in the present preferred practice we maintain a transversely inclined bed, from which the h avy impurities, as soon as they settle from the bed onto the deck, are impelled diagonally toward and out of upper side edge of the bed, there being thus effected a continuous fractional discharge of the settled impurities, the larger pieces of which settle out at the rear and b gradually decreasing sizes forwardly along the table to a minimum at or near the front end of the bed. Thus a concentration of the separated heavy materials within the bed is avoided. In such a bed, the superior stratum of purified coal flows freely forwardly along the bed, growing in volume and thickness, and to a large degree larger pieces tend toward the bottom of said stratum, with some possible tendency toward remixturo. With a bed and general process of the kind described, the separating partitions at the rear of the bed and table will be spaced apart sufficiently far to permit the largest pieces of impurities to slide freely along therebetween, and they will be gradually set closer together forwardly along the table, spaced apart throughout only sufficiently to permit the free passage behind them of the impurities settling at that particular point on the table.

This structure and operation of the separating partitions is fully described and claimed in our copending application Ser. No. 483,857, filed as of even date herewith.

Referring now in detail to the present preferred manner of carrying out our novel process, and to a mechanism adapted for carrying it out, same is exemplarily disclosed and described in connection with a table of the type shown in the copending application of Richard Peale, Ser. No. 389,722, filed August 31, 1929, although so far as concerns the main features of the invention, it may be practiced with other kinds and constructions of tables.

The means for maintaining the bed of materials, and progressing it forwardly, for vibrating the bed and forcing the lifting and loosening air currents therethrough, may be of any known or suitable form, so far as concerns many features of the present invention.

In the exemplary embodiment thereof, a table is shown having an air-pervious deck 1, which is preferably transversely-inclined upwardly in the direction of travel of the settled heavy impurities and preferably also forwardly in the direction of travel of the superior flotant stratum of coal. This deck is supported on a suitable vibratable or reciprocable frame which is pivotally mounted at either side upon two series of backwardly and upwardly-inclined pivoted arms 6. The lower ends of the arms 6 are in turn pivotally mounted upon a stationary frame 11, which also constitutes the frame for the lower non-vibrating part of the air chamber. This frame comprises side and end members, and is longitudinally variably inclinable for the purpose of longitudinally inclining the bed of materials. Accordingly, it is shown pivotally mounted at its rear end 12, and along either side it is supported by a series of screw rod supports 13 and 14, of any known or other suitable form. These supports may be turned to vary the longitudinal inclination of the frame 11 and therewith of the table deck 1 upon which the forwardly-progressing bed of materials is supported. The pivoted supporting arms 6 render the deck 1 and its associated parts longitudinally vibratable or reciprocable upon the tiltable frame 11. The table vibrating means may be of any desired or convenient form, and as shown, an eccentric 15 is fixed to rotate on a shaft 16, and a rod 17 is conheated at one end to the eccentric and at its other end to the rear end of the table. Thereby the desired reciprocatory movement is imparted to the table.

Means are provided for maintaining upon the table a forwardly-progressing bed of substantial thickness of the raw coal, or other material undergoing separation or purification. Means for maintaining such a bed is shown more or less diagrammatically as including a hopper 18, a variable speed feed-out device 19, and a chute 20 for delivering the raw coal, in variably regulated quantity, to the rear end of the bed on table 1.

The means for providing the loosening and lifting air currents and forcing same upwardly through the bed may likewise vary widely in form and structure, and as shown, an air chamber 29 is supported in the frame 11, and this air chamber is connected to the vibrating table structure by a flexible air-tight juncture 30. At its rear end, chamber 29 communicates by a flexible connection 31 with the duct 32 of a fan 33. Suitable regulating devices may be provided if desired, and as shown herewith a series of rotatable or pivoted valves 34 may be provided in the chute 32; and additional or other air current regulating means may be employed, as desired.

The separated and settled refuse is preferably discharged from the table by the shortest and quickest route. As embodied, the table is supplied with a plurality of refuse-discharging boxes 41, arranged along one of the side edges of the table, as shown and described in certain of our copending applications, and in those of Kenneth Davis. See for example our application S. N. 326,878 and Davis application S. N. 200,080. Thus the settled impurities are impelled diagonally across the table and are expelled from the side edge of the bed. The discharge boxes ll are located along the side of the upper bedretaining wall of the table, and an air header 44 receives air from the fan chute, or the rear part of the air chamber, and the air from the header 44 is supplied by flexible conduits 46 to the refuse boxes 41. This acts to insure discharge of the rock and other impurities only, and to prevent discharge of coal, in a known manner.

The form of table or deck 1 which we preferably employ in carrying out our invention is shown in plan in Figs. 4 to '7. This table is relatively long and narrow and has a rear bedretaining wall 47 and side bed-retaining walls 48 and 49. The spillage edge 50 for the purified coal is preferably diagonally arranged at the forward end of the table, and preferably occupies a very large proportion of the length of the table. This gives a very long spillage edge for the purified coal and at the same time permits a protracted period for action upon the less readily separable components or sizes of the intermixed materials. The early purified coal will be discharged from the rear part of the spillage edge 50, but the separating action will be continued forwardly along the bed, in connection with the further separating partitions, while the purified coal is discharged progressively along the spillage edge.- The separating partitions in this type of table are forwardly and transverselyinclined, their rear ends starting some against the rear retaining wall 4'7, others against the side retaining wall 48, and others starting from the spillage edge 50, as will be clear from Figs. 4 and 5.

The present invention operates advantageously in connection with sub-aereal air regulation, preferably throughout the entire bed. A form of sub-aereal zoning the same or similar to that shown in some of our earlier copending applications is preferred. A plurality of sub-aereal air chambers 52 are formed directly beneath the air-pervious deck 1, and regulable or settable means for controlling the passage of the air through the individual sub-aereal chambers is provided. As shown, the bottom plate 57 of the respective sub-aereal air chambers is provided with a plurality of perforations, which may be fitted with stoppers or corks 58 to any desired extent, thereby regulating the air current flow through the particular sub-aereal chamber as may be desired. It will be understood, of course, that the form of air-admission control for the sub-aereal chambers may be varied as desired.

The character of the lifting and loosening air currents forced through the bed of materials undergoing separation may be widely varied, as may b found desirable or efficient. In the present exemplified embodiment, we have shown a pulsating air current action, such as is disclosed in said copending application of Richard Peale, Ser. No. 389,722, and this need not be described in full detail. For this purpose a rotary butterfly valve or shutter 59 is mounted on a shaft 68, journaled transversely across the air chamber. The shutter or butterfly valve 59 rotating within the chamber, alternately leaves it practically wide open and then closes it practically completely, and correspondingly varies the air action through the bed. The valve actuating means comprises a sprocket chain drive 61, which runs over a sprocket wheel 62, fixed on the shaft 60, and over a sprocket wheel 54, fixed on the shaft 16, already described. By this structure and arrangement, a pulsating action of the air current along the bed may be effected, if desired. If the drive for the shutter 59 is silenced and the shutter removed or left in horizontal position, the same mechanism will provide a steady or uniform air current.

The variation in the spacing of the separati--g partitions, as an improved constructional feature, is harmonized with the structure and position of the sub-areal chambers, and thereby a very fine regulation of the lifting and loosening air currents in relation to the interspacing between the separating partitions is effected. Such an arrangement is shown in Fig. 5 of the drawings, where the widest interspacing of separating partitions is indicated by numeral 64, and the forward partition wall of the separating partition, inclined in the same direction, is indicated by the broken line 65. The next degree of interspacing between the separating partitions is indicated by 70, and the forward separating wall of the subareal chamber is indicated by '71, this wall being inclined in the same direction as the separating partitions. The side walls of the table likewise constitute walls of the sub-areal air chambers, and there may be cross-partitions between such partitions as 65 and 71, as shown in Fig. 2 of the drawings, for the chambers 49. Successive similar arrangements of variations in interspacing of separating partitions and the boundary walls of sub-areal chambers are indicated respectively by the pairs of reference numerals 72, '73 and '74, and 75 and "6.

In practicing our invention, we preferably employ a table deck of gradated or zoned air perviosity, and preferably such a table with the air current intensity decreasing forwardly. In Fig. 7 there is diagrammatically shown a zoning of a table into four degrees of air erviosity, the varying degrees being indicated as A, B, C and D. It will be understoodthat the radations may be more gradual as by varying the her and size of air perforations in the deck plate 1.

It will be clear from the foregoing description, and as already disclosed in prior applications of our assignee, as for example, our joint application S. N. 5985316 filed November 1930, the gradations and relative ar as of t e zones A, B, 0,13, etc. will preferably, in practice, be calibrated and dimensioned substantially according to the rela tive quantities of different sizes of pieces and particles in the raw coal being treated, and especially the relative quantities of the diiierent sizes of the heavier impurities. For example, when preliminary tests of the runoi-n1ine coal show a relatively large proportion of coarse heavy ma-' terial, the rear zone A of greatest air intensity will be accordingly large in area to provide adequate air action for the stratification of the large quantity of coarse impurities. Correspondingly the other zones of air intensity will be calibrated and proportioned according to the relative quantities of intermediate and smaller sized impurities in the raw coal.

As previously stated one of the main objectives of the present invention is the control of the ficwage or confluence of materials in the bed, and by controlling, directing and changing the path or paths of, and also by relatively retarding the travel of, certain sizes or other elements of the bed, to facilitate and render more eiilcient certain difficult phases of separation and purification.

In the embodied form of such means, directive and retardant devices act on iiotant and forwardly flowing parts or elements of the bed which are still more or less in intermixture, and usually said means are advantageously applied in connection with the separating partitions. Usually these directive and retardant devices are applied at fairly widely spaced apart positions along the bed, and accordingly most of the separating partitions 100 are of normal height and extend forwardly and diagonally on the deck from the lower side, terminating a short distance from the upper side wall of the table. Certain of the separating partitions, marked 101, are continued to the outer wall adjacent to the forward ends of the refuse-discharge openings l"2, as at 103, thereby insuring the discharge of the heavy material sliding along the deck into the adjacent refuse-discharge opening. The novel retarding and directing devices for the ilotant material are preferably applied to these separating partitions.

These relatively long separating partitions 101 rave portions 104, rojecting vertically about, say, twice the height of the main portion 101 and extending from the side wall 48 to some median point. The length of these high parts 104- vary along the table, as shown exemplarily in Fig. 4, being relatively short near the rear of the deck and increasing in length forwardly thereof.

These members 104 extend upwardly into the intermediate strata of the bed, especially along the lower side thereof, and thus partially and temporarily retard forward and inward transverse progress of fiotant material. The material thus caught by the extensions 104 is guided transversely toward the outer or high side of the deck,

so that the fine, heavy impurities which are temporarily ilotant in the upper and intermediate strata have additional opportunity to sink to the deck and behind a separ ng partition, and are thus prevented from. reach1....g the lower side of the deck. When the fiotant material has worked laterally beyond the of vertical extension 1%, much of the fine heavy material therein will have settled low enough to travel behind the lower portion 101 and will be directed to the adjacent refuse-discharge opening, while the coal particles will remain iiotant and resume their normal course forwardly.

As the bed progresses forwar ly the confluence of fines toward the lower side of the deck becomes more marked, and accordingly the vertical extensions 104 on the separating partitions 1.01 are made progressively longer forwardly of the deck. Thus fine impurities are prevented from working too far toward the inner side of the bed before sinking behind the separating partitions.

Cfi

In addition, the extensions 104 in preventing confluence of fine coal toward the inner side of the deck, tend to maintain more uniform size dis tribution and fluidity of the bed. Some of the fine coal is redirected toward the center and outer side of the bed, and so voids between the pieces of coarse coal are occupied by the fine coal. This re-distribution and maintenance of fine coal among the coarser pieces is desirable, as the air has less opportunity to lift fine heavy material upwardly into the coarse coal, and uniformity of air action and consequent uniformities in bed fluidity are promoted.

Like means are preferably employed for coun teracting the tendency of the temporarily fiotant particles of heavy impurities, rior to settling on the deck, to work toward the lower side of the deck and away from the refuse-boxes. As shown, for this purpose, the outer portion of separating partitions 103 are provided with vertical extensions 106. These extensionsare preferably rela tively short and are spaced a substantial distance from the outer side wall 49, preferably terminating substantially on line with the outer ends of the intervening separating partitions 100. These extensions 106 operate to catch temporarily flotant impurities near the refuse boxes and guide them thereto, preventing them from flowing over the separating partitions and working toward the lower side of the bed. Usually extensions 106 are made progressively shorter forwardly of the deck, for the reason that as the bed progresses forwardly the impurities become more and more settled, while the coarse coal has largely worked toward the outer side of the deck. That is, extensions 106 are shorter as the proportion of large coal increases in their vicinity longitudinally of the bed, to avoid their guiding such coal into the refuse boxes. For the same reason the extension members 106 are terminated short of the outer side wall so that pieces of coal temporarily engaged thereby will have opportunity to resume their forward course within the wall 49 and over the relatively low portions 103 of the separating partitions.

In practice, the forms, numbers and positions of the vertical extensions on the separating partitions willbe varied as may be desired or necessary in treating different coals. Extensions 104 and 106 may be used alone, and the relative heights and lengths of these extensions may be varied according to conditions. While we have shown and described the vertical extension members 104 and 106 applied only to the separating partitions 101, which extend to the refuse boxes, it will be understood that either or both of these may be applied to the shorter intermediate separating partitions 100. It will be clear also that the invention is not limited to the use of such extensions in the areas or positions shown, but that the separating partitions may be modified in height wheresoever the conditions of the bed during the separating process require same.

While in Fig. 4 we have shown the retarding and directing devices 104 and 106 applied to separating partitions 101 which are spaced uniformly from each other along the table, it will be understood that similar directive and retardant devices may be utilized with a separating deck having a differential interspacing of the separating partitions. For example, some or all of the separating partitions spaced as shown in Fig. 5 may be provided with the directive and retardant devices shown and described in connection with Figs. 4 and 6.

74 and 76 are of progressively decreasing heights,

as shown in Fig. 9 for example, the directive and retardant devices 104 and 106 will likewise be proportionately decreased in height, as determined by their longitudinal locations on the deck. It will be understood that the variations in height of the separating partitions and of their built-up retardant and directive portions will preferably be calibrated with the size ranges and characteristics of the particular coal to be treated.

By another feature of our invention, we provide for the more certain and rapid settlement and discharge of fine impurities from the bed, particularly when the quantity of such fine heavy particles in the raw coal is relatively great. As embodied (Fig. 8), the separating partitions 101, which extend the full width of the deck to 2. refuse-discharge opening 102, are provided with means for enhancing the settling of the fine heavy particles and the maintenance thereof in the settled stratum until discharged. In practice, a relatively very narrow strip or area 110 of the deck immediately in the rear of a separating partition 101 is made air-retardant or impervious, to provide an area of relatively very low air intensity acljacent the rear face of the separating partition, and thus to effect a downward filtration and settlement of the fine impurities in that area. A considerable quantity of fine heavy particles is thus caused to settle behind and travel along the v separating partitions 101 and to be directly discharged through the refuse openings 102. The strips 110 may be faced oppositely from the separating partitions 101, that is, toward the rear of the deck, whereby the horizontal foot portions of L the angles form the impervious strips 110. The shorter and more numerous separating partitions 100 are faced in the opposite direction so that the horizontal foot members 111 extend toward the front of the table in the direction of the bed travel and the reciprocation thrust, and thus do not catch and hold the line heavy particles. This construction of the separating partitions 100 is in accordance with the disclosure of copending application of Richard Peale, Ser. No. 389,722, filed August 31, 1929, and as therein described is the better practice throughout the greater extent of the deck, preventing undue packing and clogging of the fine material. However, by settling the spaced-apart separating partitions 101 in the reverse position, the impervious strips 110 help to make a clean-up of the fine refuse at the end of each refuse discharge opening 102.

It will be understood that the impervious or air-retarding strips 110 constitute a relatively exceedingly small proportion of the area of the deck and that the air currents passing upwardly around these strips are deflected by the material in the bed above the separating partitions so that substantially no dead spaces exist throughout the A depth of t .e bed. In Figs. 6 and 8 the width and thicknesses of the individual separating partitions are greatly exaggerated with respect to the width and length of the pervious deck. In actual practice the decks are from approximately 45 to '75 feet in length and from 4 to 7 feet in width, depending upon their capacities, while the strips and 111 are one inch or less in width. However, the relatively narrow and shallow sheltered spaces provided by the strips 110 are very effective in attracting and retaining fine heavy particles and effecting their prompt discharge as described.

The invention in its broader aspects is not limited to the specific mechanisms shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages.

What we claim is:

1. The process of separating intermixed divided materials varying relatively greatly in size, such as run-0f-mine coal, which comprises maintaining a forwardly progressing, transversely inclined bed of substantial depth of the materials, effecting separation with fiotation of a lighter material and settlement of heavier material, impelling the settled heavier material to discharge by friction and inertia and impelling flotant material in vertically intermediate strata in a direction transverse to its natural flow to promote complete separation of the materials.

2. The process of separating intermixed divided materials varying relatively greatly in size, such as run-of-mine coal, which comprises maintaining a forwardly progressing, transversely inclined bed of substantial depth of the materials, effecting separation by superposed stratification with flotation of a lighter material and settlement of a heavier material, impelling the settled heavier material to discharge by friction and inertia and directing flotant material in intermediate strata transversely for a part only of the width of the bed to complete separation of the materials.

3. The process of separating intermixed divided materials varying relatively greatly in size, such as ru'n-of-mine coal, which comprises maintaining a forwardly progressing, transversely inclined bed of substantial depth of the materials, effecting separation by superposed stratification with flotation of a lighter material and settlement of a heavier material, impelling the settled heavier material to discharge by friction and inertia and retarding the forward flow of fiotant material in intermediate strata in a part only longitudinally of the bed to promote complete separation of the materials.

4. The process of separating intermixed divided materials varying relatively greatly in size, such as run-of-mine coal, which comprises maintaining a substantially deep, forwardly progressing, transversely inclined bed of the materials, effecting separation with flotation of a lighter material and settlement of a heavier material, impelling the settled heavier material to discharge by friction and inertia and deflecting the flow of intermixed flotant fines beneath superposed fiotant lighter material to promote complete separation thereof.

5. The process of separating intermixed divided materials relatively greatly in. such as run-of-mine coal, which comprises maintaining a forwardly progressing, transversely inclined bed of the materials, effecting separation with flotation of a lighter material. and settlement of a heavier material, impelling the settled heavier material to discharge by friction and inertia and deflecting the flow of intermixed flotant fines upwardly and beneath superposed fiotant purified lighter material, partly across 7. The process of separating unsized run-ofmine coal which comprises maintaining a forwardly progressing, transversely inclined bed of substantial depth thereof, subjecting the bed to lifting and loosening air currents and thereby initially effecting a stratification wherein the coarser impurities settle to the bottom of the bed, While some of the finer impurities remain temporarily fiotant and in intermixture in intermediate fiotant strata, impelling the settled impurities along the bottom of the bed to discharge while progressing the flotant strata in a different direction to discharge, and deflecting selected portions of the intermediate flotant strata in the direction of movement of the settled impurities to thereby prevent fine impure particles from congregating in a portion of the bed remote from the discharge locus.

8. A mechanism for separating intermixed divided materials including in combination a transversely inclined air-pervious table, means for feeding raw coal to the table, means for progressing said coal in a bed forwardly along the table, means for passing air currents upwardly through the bed, a plurality of forwardly and transversely disposed separating partitions on the table for guiding settled heavy material at an angle to the fiow of the flotant material in the bed, a plurality of said partitions being of increased height along the lower side of the table so as to act also on the intermediate fiotant strata of the bed in said portion of the table, and the higher portions of said latter partitions nearer the front end of the bed being greater in length than those near the feed end of the bed, and means for maintaining the top of the bed substantially above the tops of said partitions.

9. A mechanism for separating intermixed divided materials including in combination a transversely inclined air-pervious table, means for feeding raw coal to the table, means for progressing said coal in a bed forwardly along the table, means for passing air currents upwardly through the bed, a plurality of forwardly and transversely disposed separating partitions on the table and spaced progressively closer together toward the discharge end of the table for guiding settled heavy material at an angle to the fiow of the flotant material in the bed, a plurality of said partitions being of increased height along the lower side of the table so as to act also on the intermediate flotant strata of the bed in said portion of the table, and means for maintaining the top of the bed substantially above the tops of said partitions.

RICHARD PEALE. REMBRANDT PEALE, JR. 

